JP2003295570A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus where toner is hardly stuck to the case of a developing cartridge. <P>SOLUTION: The color image forming apparatus has a plurality of developing cartridges 42 attachably/detachably attached to a rotating body main body 41, is equipped with a rotary developing device 40 selectively imparting the toner to a latent image on an image carrier 21 and developing the latent image by the developing member 43 of the cartridge 42 by the intermittent rotation of the main body 41, and is equipped with a toner suction duct 80 having a 1st toner suction port 81 arranged on a downstream side in the rotating direction of the image carrier 21 with respect to a developing position D for the image carrier by a developing member, and having a 2nd toner suction port 82 arranged near the cartridge 42 on a more downstream side in the rotating direction of the image carrier 21 than the 1st toner suction port. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer, a facsimile, which forms a color image by using electrophotography.
The present invention relates to a color image forming apparatus such as a copying machine. In particular, the present invention relates to a technique for preventing scattered toner in the developing section.

[0002]

2. Description of the Related Art Generally, as a color image forming apparatus using electrophotography, a photosensitive member (image carrier) having a photosensitive layer on its outer peripheral surface, and a charging means for uniformly charging the outer peripheral surface of this photosensitive member. An exposing unit that selectively exposes the outer peripheral surface uniformly charged by the charging unit to form an electrostatic latent image; and a plurality of colors that are developers as the electrostatic latent image formed by the exposing unit. Visible toner (toner image)
There is known a color image forming apparatus including a developing device. The developing device includes a rotating body and a plurality of developing cartridges that are detachably attached to the rotating body, and by intermittent rotation of the rotating body, a developing member of the developing cartridge (for example, Developing roller)
There is known a rotary developing device which selectively applies a toner of each color to the latent image on the image carrier to develop the latent image.

[0003]

When the image on the image bearing member is being developed by the developing device, toner is often scattered in the form of mist at the developing portion. The mist-like toner is scattered by the air flow that is generated by the rotation of the image carrier and is directed to the downstream side in the rotation direction. Further, in the case of the rotary developing device as described above, a plurality of developing cartridges (developing colors) are switched and developed by intermittent rotation of the rotating body, so that toner is easily scattered during the switching operation, and this toner is also The air flow that is generated by the rotation of the image bearing member and is directed toward the downstream side in the rotation direction easily moves toward the downstream side in the rotation direction of the image bearing member. In addition, the air flow toward the downstream side in the rotating direction generated by the rotation of the rotating body in the developing device also tends to flow toward the downstream side in the rotating direction of the rotating body.
The conventional image forming apparatus has a problem that the scattered toner adheres to the surface of the case of the developing cartridge. Since the developing cartridge is a consumable item and the replacement work is performed by the user, there is a problem that the user's hand is soiled with the toner during the replacement work.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a color image forming apparatus in which toner hardly adheres to the case of a developing cartridge.

[0005]

In order to achieve the above object, a color image forming apparatus according to a first aspect of the present invention comprises a rotating body, and a plurality of developing cartridges detachably attached to the rotating body. An image forming apparatus having a rotary developing device for selectively applying toner to a latent image on an image carrier by a developing member of a developing cartridge to develop the latent image by intermittent rotation of the rotating body, A first toner suction port arranged on the downstream side in the rotation direction of the image carrier with respect to the development position of the image carrier by the developing member, and a developing cartridge on the downstream side in the rotation direction of the image carrier with respect to the first toner suction port. And a toner suction duct having a second toner suction port arranged near the. A color image forming apparatus according to a second aspect is the color image forming apparatus according to the first aspect, wherein the second toner suction port is arranged on the downstream side in the rotation direction of the rotating body. The color image forming apparatus according to claim 3 is the color image forming apparatus according to claim 1 or 2, wherein an opening area of the first toner suction port is larger than an opening area of the second toner suction port. And
The color image forming apparatus according to claim 4 is the color image forming apparatus according to claim 1,
Alternatively, in the color image forming apparatus described in 3,
It is characterized in that a plurality of suction ports are provided.

[0006]

According to another aspect of the present invention, there is provided a color image forming apparatus having a rotating body and a plurality of developing cartridges which are detachably mounted on the rotating body. An image forming apparatus comprising a rotary developing device for selectively applying a toner to a latent image on an image carrier to develop the latent image on the image carrier by a developing member of a developing cartridge, A first toner suction port arranged on the downstream side of the image carrier in the rotation direction, and a second toner suction port arranged near the developing cartridge on the downstream side of the first toner suction port in the rotation direction of the image carrier. According to the color image forming apparatus of the first aspect, the following effects can be obtained. That is, when the image on the image bearing member is being developed by the developing device, the toner is scattered like mist at the developing portion.
The toner is sucked by the first toner suction port of the toner suction duct, which is arranged on the downstream side (the side where the toner flows) in the rotational direction of the image carrier with respect to the developing position. Moreover, if
Even if some of the toner is not completely sucked by the first toner suction port and further flows to the downstream side, the toner is located downstream of the first toner suction port in the rotation direction of the image carrier. The toner is sucked by the second toner suction port arranged near the. Similarly, even if toner is scattered during the developing color switching operation by the rotary developing device, this toner is sucked by the first suction port and the second suction port as described above. Therefore, according to this color image forming apparatus, the scattered toner is less likely to adhere to the surface of the case of the developing cartridge, and the user's hand is less likely to be contaminated with the toner when the cartridge is replaced. Moreover, as a result of the scattered toner being sucked by the first and second suction ports, toner contamination in the image forming apparatus is significantly reduced. According to the color image forming apparatus of the second aspect, in the color image forming apparatus of the first aspect, the second toner suction port is arranged on the downstream side in the rotation direction of the rotating body, and therefore The following effects can be obtained. That is, as described above, the toner scattered during the switching operation of the developing cartridge is apt to move toward the downstream side in the rotation direction due to the air flow generated by the rotation of the rotating body in the developing device. According to this, since the second toner suction port is arranged on the downstream side in the rotation direction of the rotating body, the scattered toner can be sucked efficiently. According to the color image forming apparatus of claim 3, in the color image forming apparatus of claim 1 or 2, the opening area of the first toner suction port is larger than the opening area of the second toner suction port. Therefore, the following operational effects are further obtained. That is, if the opening area of the first toner suction port is
If the opening area of the second toner suction port is smaller than that of the second toner suction port, the scattered toner is more sucked by the second toner suction port, and the second suction port rotates the image carrier relative to the developing position. Since the toner is disposed near the developing cartridge on the downstream side in the rotation direction of the image carrier further than the first toner suction port disposed on the downstream side in the direction, the case of the developing cartridge in the process of the scattered toner reaching the second suction port. There is a greater risk that it will adhere to the. On the other hand, according to the color image forming apparatus of the third aspect,
Since the opening area of the first toner suction port is larger than the opening area of the second toner suction port, most of the scattered toner is sucked by the first toner suction port.
Only a small amount of scattered toner goes to the second suction port,
This toner will be sucked by the second suction port as described above. Therefore, the possibility that toner will adhere to the surface of the case of the developing cartridge is surely reduced. According to the color image forming apparatus of claim 4,
In the color image forming apparatus described in 1, 2, or 3,
Since the plurality of second suction ports are provided, the toner toward the second suction port is gradually sucked by the plurality of second suction ports. Therefore, the possibility that toner will adhere to the surface of the case of the developing cartridge is more reliably reduced.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic front view showing an internal structure of an embodiment of a color image forming apparatus according to the present invention, and FIG. 2 is an enlarged view of a main part thereof. As shown in FIG. 1, the image forming apparatus is an apparatus capable of forming a full-color image on both sides of a sheet, and includes a case 10 and an image carrier unit 20 housed in the case 10.
And an exposure unit 30 as an exposure unit and a developing device 4
0, an intermediate transfer body unit 50, and a fixing unit 60.

The case 10 is provided with a frame (not shown) of the apparatus main body, and each unit and the like are attached to this frame.

The image carrier unit 20 includes a photoconductor (image carrier) 21 having a photosensitive layer on its outer peripheral surface, and a corona discharge charger 22 as a charging means for uniformly charging the outer peripheral surface of the photoconductor 21. The outer peripheral surface of the photoconductor 21 uniformly charged by the charging means 22 is selectively exposed by the laser light from the exposure unit 30 to form an electrostatic latent image. Toner as a developer is applied to the latent image by the developing device 40 to form a visible image (toner image), and this toner image is transferred to the intermediate transfer member (intermediate transfer belt) 51 of the intermediate transfer member unit 50 at the primary transfer portion T1. The primary transfer is performed, and further, the secondary transfer section T2 performs the secondary transfer on the sheet to be transferred.

Inside the case 10, there is a conveying path 16 for conveying a sheet having an image formed on one surface by the secondary transfer section T2 toward a sheet discharging section (sheet discharging tray section) 15 on the upper surface of the case 10. A return path 17 is provided for returning the sheet conveyed by the conveying path 16 toward the sheet discharge section 15 to the secondary transfer section T2 so as to switch back the sheet and form an image on the other surface. At the bottom of the case 10, there are provided a paper feed tray 18 for stacking and holding a plurality of paper sheets, and a paper feed roller 19 for feeding the paper sheets one by one toward the secondary transfer portion T2.

The developing device 40 is a rotary developing device,
A plurality of developing cartridges are detachably attached to the rotating body 41. In this embodiment, the developing cartridge 42Y for yellow, the developing cartridge 42M for magenta, and the developing cartridge 42 for cyan are used.
C and a black developing cartridge 42K are provided, and the developing body 43 of the developing cartridge 42 is selectively brought into contact with the photoconductor 21 by rotating the rotator body 41 in the arrow direction at a pitch of 90 degrees. It is possible to selectively develop the surface of the photoconductor 21 by (or closely facing).

The intermediate transfer body unit 50 includes a unit frame (not shown), a driving roller 54, a driven roller 55, and a primary transfer roller 5 which are rotatably supported by the frame.
6, a guide roller 57 for stabilizing the state of the belt 51 at the primary transfer portion T1, and a tension roller 58
And the intermediate transfer belt 51 wound around these rollers and stretched, and the belt 51 is circularly driven in the direction of the arrow in the figure. Photoconductor 21 and primary transfer roller 56
The primary transfer portion T1 is formed between
The drive roller 54 and the secondary transfer roller 1 provided on the main body side
The secondary transfer portion T2 is formed at the pressure contact portion with 0b. The secondary transfer roller 10b can be brought into and out of contact with the drive roller 54 (and thus with respect to the intermediate transfer belt 51), and when it comes into contact with the drive roller 54, the secondary transfer portion T2 is formed.
Therefore, when forming a color image, toner images of a plurality of colors are superposed on the intermediate transfer belt 51 in a state where the secondary transfer roller 10b is separated from the intermediate transfer belt 51, and then a color image is formed. The secondary transfer roller 10b comes into contact with the intermediate transfer belt 51, and the paper is supplied to the abutting portion (secondary transfer portion T2), whereby the image is transferred onto the paper.

In the image forming apparatus as described above, for example, when the image on the image carrier 21 is being developed by the developing device 40, as shown in FIG. 2, its developing portion (developing position). In D, the toner is often scattered in the form of mist, and this mist-like toner is scattered by the air flow (see arrow a1) toward the downstream side in the rotation direction generated by the rotation of the image carrier 21. Further, in the case of the rotary developing device 40 as described above, the plurality of developing cartridges 42 (Y, M, C, K) are switched and developed by the intermittent rotation of the rotating body 41, so that the toner is scattered during the switching operation. This toner is also liable to move to the downstream side in the rotation direction of the image carrier 21 due to the air flow (see arrow a1) toward the downstream side in the rotation direction generated by the rotation of the image carrier 21. Also,
The airflow (see arrow a1) toward the downstream side in the rotational direction generated by the rotation of the rotary body 41 (and thus the developing cartridge 42 (Y, M, C, K)) in the developing device 40 is also downstream in the rotational direction of the rotary body 41. Therefore, if no measures are taken (assuming that the first and second toner suction ports described later are not provided), the scattered toner as described above is the case of the developing cartridge 42. Since the developing cartridge 42 is a consumable item and needs to be replaced by the user, the user's hand will be contaminated during the replacement work.

Therefore, in this embodiment, as shown in FIG. 2, the first roller is arranged downstream of the developing position D of the developing roller 43, which is a developing member, with respect to the image carrier 21 in the rotational direction of the image carrier 21. 1 toner suction port 81 and this first
The second cartridge disposed near the developing cartridge 42 on the downstream side of the toner suction port 81 in the rotation direction of the image carrier 21.
A toner suction duct 80 having a toner suction port 82 is provided.

The toner suction duct 80 is provided in a curved shape (substantially semi-cylindrical shape) that covers the rotary developing device 40 for about half a circumference.

In this embodiment, the rotation direction of the image carrier is clockwise, and the rotation direction of the rotor body 41 in the developing device 40 is counterclockwise. Therefore, the moving directions of both surfaces in the developing section D are the same. (Upper in the figure). Therefore, the second toner suction port 82 is arranged on the downstream side in the rotation direction of the rotating body 41.

FIG. 3 is a plan sectional view mainly showing the toner suction duct 80. As is clear from FIGS. 2 and 3, the opening area of the first toner suction port 81 is larger than the opening area of the second toner suction port 82.

A fan 83 is provided at the end of the toner suction duct 80, and the scattered toner is sucked from the first and second suction ports 81 and 82 by the operation of the fan 83. That is, as shown in FIG. 4, while the image on the image carrier 21 is being developed by the developing roller 43, the toner is scattered in the form of mist at the developing portion D. On the other hand, the toner is sucked by the first toner suction port 81 of the toner suction duct 80, which is arranged on the downstream side of the image carrier 21 in the rotation direction (the side where the toner flows), as indicated by the arrow a2. Also, if this first
Even if some toner is not completely sucked by the toner suction port 81 and further flows to the downstream side as indicated by an arrow a3, the toner is rotated by the image carrier 21 more than the first toner suction port 81. Developing cartridge 4 on the downstream side in the direction of
The second toner suction port 82 arranged near 2 is sucked as indicated by an arrow a4. Similarly, even if toner is scattered during the developing color switching operation by the rotary developing device 40, the toner is sucked by the first suction port 81 and the second suction port 82 as described above.

As described above, the toner scattered during the switching operation of the developing cartridge 40 is the air flow generated by the rotation of the rotating body 41 (see FIG. 2) in the developing device, and is the downstream side in the rotational direction (in this embodiment, the developing unit). The second toner suction port 82 is arranged on the downstream side in the rotation direction of the rotating body 41, so that the scattered toner is efficiently sucked.

Since the opening area of the first toner suction port 81 is larger than the opening area of the second toner suction port 82, most of the scattered toner is the first toner suction port as indicated by the arrow a2. Only a small amount of scattered toner is sucked by 81 and goes to the second suction port 82, and this toner is sucked by the second suction port 82 as indicated by arrow a4. Therefore, the developing cartridge 4
The risk that toner will adhere to the second case surface 42a is reliably reduced.

Further, as shown by phantom lines 82 'and 82''in FIG. 3, a plurality of second suction ports 82 can be provided.
With this configuration, the second suction ports 82 ', 82, 8
The toner that goes toward 2 ″ is the plurality of second suction ports 82 ′,
82, 82 ″ sucks in stages. Therefore, the case surface 4 of the developing cartridge 42
The risk that toner will adhere to 2'is more reliably reduced.

As shown in FIGS. 2 and 3, a filter unit F which can be inserted into and removed from (removable from) the front surface of the image forming apparatus (see FIG. 1) is provided in the middle portion of the toner suction duct 80. First and second suction ports 81, 82
The toner sucked from is filtered by the filter unit F, and the cleaned air is discharged to the outside of the apparatus by the fan 83.

Further, in this embodiment, in order to make the flow of the air smoother, a blowing means is provided.
FIG. 5 is a view showing an air blowing unit, and is a perspective view showing the image carrier unit 20 and the air blowing unit 70 removed from the apparatus main body. FIG. 6 is a rear view of the image forming apparatus with the case 10 removed.

As shown in FIG. 5, the blower unit 70 is
The air supply fan 71 and the air supply duct 72 are provided, and the air supply port 72c of the air supply duct 72 is connected to the connection port 24 formed in the case 23 of the image carrier unit 20.
The connection port 24 is open toward the charger 22 in the longitudinal direction of the corona discharge charger 22 which is a charging means. As shown in FIG. 4, the shield plate 25 of the charger 22 is also provided.
A large number of openings 25a are provided on the developing section D side. Therefore, when the blower fan 71 is operated, the air from the blower fan 71 causes the duct 72 and the connecting port 2 to move.
4 is sprayed onto the charger 22 from the longitudinal direction thereof, and as shown in FIG.
Air is blown from a toward the developing unit D side as indicated by arrows a0 and a0 '.

Providing such a blowing means is as shown in FIG.
As shown in FIG. 4, when the developing member 43 is a non-contact type developing member that performs the developing operation without contacting the image carrier 21, the air (arrows a0, a0 ′) from the blower means
This is particularly effective because it flows to the downstream side in the rotation direction of the image carrier 21 through the gap (see reference numeral D) formed between the image carrier 21 and the developing member 43. Therefore, in this embodiment, the developing member 43 is a non-contact type developing member. The image carrier unit 20 and the blower unit 70 as described above are detachably attached to the apparatus main body, and in the attached state, as shown in FIG. 6, the blower fan 71 is arranged as shown. .

According to the color image forming apparatus as described above, the following operational effects can be obtained. (A) The rotating body main body 41 and a plurality of developing cartridges 42 that are detachably attached to the rotating body main body 41. The developing cartridge 42 (Y, M, The developing member 43 of (C, K) includes a rotary developing device that selectively applies toner to the latent image on the image carrier 21 to develop the latent image.
With respect to the developing position D, the first toner suction port 81 is arranged on the downstream side in the rotation direction of the image carrier 21, and the developing cartridge 42 is located downstream of the first toner suction port 81 in the rotation direction of the image carrier 21. Since the toner suction duct 80 having the second toner suction port 82 arranged in the vicinity is provided, the following operational effects can be obtained. That is,
While the image on the image carrier 21 is being developed by the developing device 40, the toner is scattered in a mist state at the developing section D. This toner is in the rotational direction of the image carrier 21 with respect to the developing position D. The toner is sucked by the first toner suction port 81 of the toner suction duct 80 arranged on the downstream side (the side where the toner flows). Moreover, even if some toner is not completely sucked by the first toner suction port 81 and further flows to the downstream side, the toner of the image carrier 21 is discharged from the first toner suction port 81. The toner is sucked by the second toner suction port 82 arranged near the developing cartridge 42 on the downstream side in the rotation direction. Similarly, even if toner is scattered during the developing color switching operation by the rotary developing device 40, the toner is sucked by the first suction port 81 and the second suction port 82 as described above. Therefore, according to the color image forming apparatus, the scattered toner causes the developing cartridge 42
It becomes difficult for the toner to adhere to the case surface 42a, and it is also difficult for the user's hand to be soiled with toner during the cartridge replacement work. Moreover, as a result of the scattered toner being sucked by the first and second suction ports 81, 82, toner contamination in the image forming apparatus is significantly reduced. (B) Since the second toner suction port 82 is arranged on the downstream side in the rotation direction of the rotating body 41, the following operational effects can be further obtained. That is, as described above, the toner scattered during the switching operation of the developing cartridge 42 is
The airflow generated by the rotation of the rotating body 41 in the developing device 40 tends to move toward the downstream side in the rotating direction. However, according to this color image forming apparatus, the second toner suction port 82 is located downstream in the rotating direction of the rotating body 41. Since it is arranged,
The scattered toner is efficiently sucked. (C) Since the opening area of the first toner suction port 81 is configured to be larger than the opening area of the second toner suction port 82, the following operational effects are further obtained. That is,
If the opening area of the first toner suction port 81 is smaller than the opening area of the second toner suction port 82, the scattered toner will be sucked more by the second toner suction port 82. The second suction port 82 is closer to the developing cartridge 42 on the downstream side in the rotation direction of the image carrier 21 than the first toner suction port 81 arranged on the downstream side in the rotation direction of the image carrier 21 with respect to the developing position D. Since the toner is disposed, the scattered toner is likely to adhere to the case of the developing cartridge 42 in the process of reaching the second suction port 82. On the other hand, according to the color image forming apparatus of this embodiment, the opening area of the first toner suction port 81 is larger than the opening area of the second toner suction port 82. Are sucked by the first toner suction port 81, and the second suction port 82
Only a small amount of scattered toner is directed to, and this toner is sucked by the second suction port 82 as described above. Therefore, the possibility that toner will adhere to the surface of the case of the developing cartridge 42 is surely reduced. (D) For example, as shown in FIG. 3, by providing a plurality of second suction ports, a plurality of second suction ports 82 ′, 82, 8 are provided.
The toner heading to the 2 ″ is the plurality of second suction ports 82 ′,
82, 82 ″ sucks in stages. Therefore, the possibility that toner will adhere to the surface of the case of the developing cartridge 42 can be more reliably reduced.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various modifications can be appropriately made within the scope of the gist of the present invention.

[0028]

According to any of the color image forming apparatuses of the first to fourth aspects, scattered toner is less likely to adhere to the surface of the case of the developing cartridge, and the user's hand is contaminated with the toner when the cartridge is replaced. Is less likely to occur. Moreover, the toner contamination in the image forming apparatus is significantly reduced. Further, according to the color image forming apparatus of the second aspect, the scattered toner is efficiently sucked. According to the color image forming apparatus of the third aspect, the possibility that toner will adhere to the surface of the case of the developing cartridge is surely reduced. According to the color image forming apparatus of the fourth aspect, the possibility that toner will adhere to the surface of the case of the developing cartridge is more reliably reduced.

[0029]

[Brief description of drawings]

FIG. 1 is a schematic front view showing the internal structure of an embodiment of a color image forming apparatus according to the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a plan sectional view mainly showing a toner suction duct 80.

FIG. 4 is a partially enlarged view of FIG.

FIG. 5 is a perspective view showing an image carrier unit 20 and a blower unit 70 removed from the apparatus main body, showing a blower.

FIG. 6 is a rear view of the image forming apparatus with the case 10 removed.

[Explanation of symbols]

21 photoconductor (image carrier) 40 rotary developing device D development position 41 Rotating body 42 Development cartridge 43 developing roller (developing member) 80 Toner suction duct 81 First toner suction port 82 Second toner suction port

Continued front page    F-term (reference) 2H077 AD02 AD06 BA09 BA10 CA16                       GA04 GA13                 2H300 EA06 EA17 EB02 EB08 EB12                       EC02 EC05 EF03 EF08 EH16                       EJ09 EJ15 EJ31 EK03 GG01                       GG02 GG03 GG43

Claims (4)

[Claims] 1. A rotating body main body and a plurality of developing cartridges detachably attached to the rotating body main body, wherein the developing member of the developing cartridge selectively serves by intermittent rotation of the rotating body main body. An image forming apparatus including a rotary developing device for applying toner to a latent image on an image carrier to develop the latent image, the device being disposed downstream of a developing position of the developing member with respect to the image carrier in a rotation direction of the image carrier. The first toner suction port and a second toner suction port disposed near the developing cartridge on the downstream side of the first toner suction port in the rotation direction of the image carrier.
A color image forming apparatus comprising a toner suction duct having a toner suction port. 2. The color image forming apparatus according to claim 1, wherein the second toner suction port is arranged on the downstream side in the rotation direction of the rotating body. 3. The color image forming apparatus according to claim 1, wherein the opening area of the first toner suction port is larger than the opening area of the second toner suction port. 4. The color image forming apparatus according to claim 1, wherein a plurality of the second suction ports are provided.